Fig. 4From: Promising role of topical caffeine mesoporous gel in collagen resynthesis and UV protection through proline assessment3D surface plots for the effect of formulation factors on a Q24, b Kp, c Jss and the Box-Cox plot for power transformation of the Jss model. SYL-C: caffeine on Syloid® 244 FP. The cumulative amount of drug permeated after 24 h, Q24; the permeation rate of caffeine at steady state, Jss; and the permeability coefficient, KpBack to article page